1. Field of the Invention
The present invention relates to processes for making a silylisocyanurate and a silylorganocarbamate. More particularly, the present invention relates to a process for making 1,3,5-tris[(trialkoxysilyl)alkyl] isocyanurates. The silylisocyanurate has utility as an accelerator or promoter for adhesion of room temperature vulcanizable organosiloxanes and silane modified polymers, as an additive for organosiloxane compositions suitable for fiber treatment and in automotive coatings. The silylorganocarbamate has utility as coupling agent for fiber glass and as agent for imparting water repellency.
2. Prior Art
U.S. Pat. No. 3,517,001 describes the hydrosilation of triallyl isocyanurate with various hydrosilanes added to the allyl groups in the presence of a catalyst such as platinum, rhodium, and the like. However, this process uses a large amount of catalyst because the isocyanuric acid ring acts as an inhibitor for the addition reaction. The addition reaction is incomplete due to the isomerization of the allyl group; and, thus, predominantly mono- and di- adducts are produced. The tri-adduct, i.e., the trisilylated isocyanurate product, is produced in low yield and is difficult to isolate.
U.S. Pat. No. 3,598,852 describes a process for making silylisocyanurate in which a haloorganosilane intermediate is reacted with a metal cyanate in the presence of a high boiling polar solvent such as dimethylformamide. Subsequently, the polar solvent is removed by vacuum stripping. However, the solvent is toxic and difficult to remove.
U.S. Pat. No. 4,880,927 describes a method for preparing silylisocyanurate in which the silylisocyanate is thermally treated or heated for cyclization to the trimer in the presence of a strongly basic catalyst such as alkali metal hydroxides or alkoxides. However, when this method is employed to prepare a silylorganoisocyanurate, it requires the isolation of toxic isocyanate and results in a highly colored product.
There is an on-going need to provide processes for preparing a silylisocyanurate, and a process for preparing a silylorganocarbamate, which processes are simple, produce the desired product in high yield, with little color and avoid the handling of toxic materials such as phosgene and isocyanate intermediates.